- ID:
- ivo://CDS.VizieR/J/A+A/375/308
- Title:
- Extension of ICRF for selected areas down to V=15
- Short Name:
- J/A+A/375/308
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of accurate positions and proper motions for 41,721 objects is provided. Objects are within areas of special astronomical interest, containing extragalactic radio sources, mostly from ICRF (see Cat. I/251), and pre-main-sequence (PMS) stars in Southern star-forming regions (Chamaeleon, Lupus and Upper Scorpius-Ophiuchus). Positions and proper motions were derived by combining current epoch positions, obtained with the Valinhos CCD meridian circle (VMC, see 1999A&AS..134..173V), with first epoch catalogues, AC2000 (I/247) and USNO-A2.0 (I/252) mainly, as well as positions from plate measurements performed with the MAMA measuring machine (Guibert J., Charvin P. & Stoclet P., 1983, in Proceedings of the 78th Colloquium of the IAU), in Paris. On average, objects with V<=14.0 have positional precisions better than 50mas in both coordinates, and 100mas near the detection limit of the VMC (V~16,0). For proper motions, average precisions are better than 4mas/year, whatever the magnitude, when delta>=-17{deg}. To the south of this declination, a magnitude dependence is verified due to a particular feature of the USNO-A2.0's epochs, providing figures of 3mas/year when V<=12.0, where the participation of AC2000 is noted, and reaching 17mas/year at the detection limit. The catalogue data is grouped by area, following the same order and identification as given in table 2 of the paper; within each area, objects are sorted by right ascension. The respective record numbers for the beginning of each area are provided in a separate table.
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Search Results
- ID:
- ivo://CDS.VizieR/J/BaltA/11/441
- Title:
- Extinction along Cam and Per border
- Short Name:
- J/BaltA/11/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction in a ~100 sq. degree area at the Camelopardalis and Perseus border is investigated. The study is based on the results of photoelectric photometry of 455 stars in the seven-color Vilnius photometric system published earlier. The nearest 100 stars with Hipparcos parallaxes show that the extinction starts to grow at a distance of 110-150pc. At a distance of 1 kpc the extinction A_v_ is within 1.2 and 2.4mag. At larger distances the extinction determination is affected by the limiting magnitude effect. At distances >1.5kpc a number of O-B stars with the extinctions between 2 and 4mag are found.
4423. Extinction in MBM12
- ID:
- ivo://CDS.VizieR/J/BaltA/11/231
- Title:
- Extinction in MBM12
- Short Name:
- J/BaltA/11/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric magnitudes and color indices in the Vilnius seven-color system for 152 stars are used to investigate the interstellar extinction in the area of the Aries molecular cloud MBM 12, coinciding with the L1454 and L1457 dust clouds. Spectral types, absolute magnitudes, color excesses, interstellar extinctions and distances of the stars are determined. The plot of interstellar extinction A_v_ versus distance shows that the dust cloud is situated at a distance of 325pc, at 180pc from the Galactic plane, and its true diameter is about 11pc. The interstellar extinction law in the area is found to be normal, typical for the diffuse dust. Ten peculiar or unresolved binary stars and some heavily reddened stars are detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/L81
- Title:
- Extinction in star-forming regions
- Short Name:
- J/ApJ/693/L81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Spitzer Infrared Spectrograph observations of G0-M4III stars behind dark clouds, I construct 5-20um empirical extinction curves for 0.3<=A_K_<7, which is equivalent to A_V_ between ~3 and 50. For A_K_<1, the curve appears similar to the Mathis diffuse interstellar medium extinction curve, but with a greater degree of extinction. For A_K_>1, the curve exhibits lower contrast between the silicate and absorption continuum, develops ice absorption, and lies closer to the Weingartner and Draine R_V_=5.5 Case B curve, a result which is consistent with that of Flaherty et al. (2007ApJ...663.1069F) and Chiar et al. (2007ApJ...666L..73C). Recently, work using Spitzer Infrared Array Camera data by Chapman et al. independently reaches a similar conclusion that the shape of the extinction curve changes as a function of increasing A_K_. By calculating the optical depths of the 9.7um silicate and 6.0, 6.8, and 15.2um ice features, I determine that a process involving ice is responsible for the changing shape of the extinction curve and speculate that this process is a coagulation of ice-mantled grains rather than ice-mantled grains alone.
- ID:
- ivo://CDS.VizieR/J/ApJ/517/264
- Title:
- Extinction in the Taurus dark cloud complex
- Short Name:
- J/ApJ/517/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the detailed distribution of extinction in a region of the Taurus dark cloud complex. Our study uses new BVR images of the region, spectral classification data for 95 stars, and IRAS Sky Survey Atlas (ISSA) 60 and 100 {mu}m images. We study the extinction of the region in four different ways, and we present the first intercomparison of all these methods, which are as follows: (1) using the color excess of background stars for which spectral types are known, (2) using the ISSA 60 and 100 {mu}m images, (3) using star counts, and (4) using an optical (V and R) version of the average color excess method used by Lada et al. We find that all four methods give generally similar results - with important exceptions. As expected, all the methods show an increase in extinction due to dense dusty regions (i.e., dark clouds and IRAS cores) and a general increase in extinction with increasing declination, due to a larger content of dust in the northern regions of the Taurus dark cloud complex. Some of the discrepancies between the methods are caused by assuming a constant dust temperature for each line of sight in the ISSA extinction maps and not correcting for unexpected changes in the background stellar population (i.e., the presence of a cluster or Galactic gradients in the stellar density and average V-R color).
- ID:
- ivo://CDS.VizieR/J/ApJ/786/113
- Title:
- Extinction law in the Cep OB3b young cluster
- Short Name:
- J/ApJ/786/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with MMT/Hectospec spectra. Color excess ratios were determined toward each of the giants using V and R photometry from the literature, g, r, i, and z photometry from the Sloan Digital Sky Survey and J, H, and K_s_ photometry from the Two Micron All Sky Survey. These color excess ratios were then used to construct the extinction law through the dusty material associated with Cep OB3b. The extinction law through Cep OB3b is intermediate between the R_V_=3.1 and R_V_=5 laws commonly used for the diffuse atomic interstellar medium and dense molecular clouds, respectively. The dependence of the extinction law on line-of-sight A_V_ is investigated and we find the extinction law becomes shallower for regions with A_V_>2.5 mag. We speculate that the intermediate dust law results from dust processing during the dispersal of the molecular cloud by the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/148/24
- Title:
- Extinction maps in the bulge from APOGEE
- Short Name:
- J/AJ/148/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic interstellar extinction maps are powerful and necessary tools for Milky Way structure and stellar population analyses, particularly toward the heavily reddened bulge and in the midplane. However, due to the difficulty of obtaining reliable extinction measures and distances for a large number of stars that are independent of these maps, tests of their accuracy and systematics have been limited. Our goal is to assess a variety of photometric stellar extinction estimates, including both two-dimensional and three-dimensional extinction maps, using independent extinction measures based on a large spectroscopic sample of stars toward the Milky Way bulge. We employ stellar atmospheric parameters derived from high-resolution H-band Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra, combined with theoretical stellar isochrones, to calculate line-of-sight extinction and distances for a sample of more than 2400 giants toward the Milky Way bulge. We compare these extinction values to those predicted by individual near-IR and near+mid-IR stellar colors, two-dimensional bulge extinction maps, and three-dimensional extinction maps. The long baseline, near+mid-IR stellar colors are, on average, the most accurate predictors of the APOGEE extinction estimates, and the two-dimensional and three-dimensional extinction maps derived from different stellar populations along different sightlines show varying degrees of reliability. We present the results of all of the comparisons and discuss reasons for the observed discrepancies. We also demonstrate how the particular stellar atmospheric models adopted can have a strong impact on this type of analysis, and discuss related caveats.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A42
- Title:
- Extinction map towards the Galactic bulge
- Short Name:
- J/A+A/550/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine the observations with the Besancon model of the Galaxy to investigate the variations of extinction along different lines of sight towards the inner Galactic bulge as a function of distance. The full results are listed in Table 1 and Table 2. These results will be also added into the BEAM calculator webpage (http://mill.astro.puc.cl/BEAM/calculator.php). For each position we give the E(J-Ks), E(H-Ks) as well as the corresponding sigma for each distance bin starting from 1 to 10kpc.
4429. Extinction of OB stars
- ID:
- ivo://CDS.VizieR/J/AN/324/219
- Title:
- Extinction of OB stars
- Short Name:
- J/AN/324/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper presents an extensive list of the total to selective extinction ratios R calculated from the infrared magnitudes of 597 O and B stars using the extrapolation method. The IR magnitudes of these stars were taken from the literature. The IR colour excesses are determined with the aid of "artificial standards", Wegner (1994MNRAS.270..229W). The individual and mean values of total to selective extinction ratios R differ in most cases from the average value R=3.10+/-0.05, Wegner (1993AcA....43..209W) in different OB associations. The relation between total to selective extinction ratios R determined in this paper and those calculated using the "method of variable extinction" and the Cardelli et al. (1989ApJ...345..245C) formulae is discussed. The R values presented in this paper can be used to determine individual absolute magnitudes of reddened OB stars with known trigonometric parallaxes.
- ID:
- ivo://CDS.VizieR/J/A+A/446/551
- Title:
- Extinctions at 7um & 15um from ISOGAL survey
- Short Name:
- J/A+A/446/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ISOGAL PSC data have been associated with near-infrared 2MASS sources, consisting a five-band photometric catalogue. In comparison with the ISOGAL-DENIS PSC catalogue, the number of fields in the ISOGAL-2MASS PSC is increased by 43 thanks to the 2MASS inclusion of the northern ISOGAL field. This point source catalogue contains all parameters of 7{mu}m or 15{mu}m from the ISOGAL PSC, together with the J H Ks bands data from the 2MASS All-Sky PSC (see the paper for a complete description). Based on the ISOGAL-2MASS PSC, the extinction laws at 7{mu}m and 15{mu}m are derived for more than 120 sightlines in the inner Galactic plane. The extinction values at 7{mu}m and 15{mu}m were in terms of the near-infrared extinction in the Ks band. The ratios that E(Ks-[7])/E(J-Ks) and E(Ks-[7])/E(Ks-[15]) are also displayed in the tables (see the paper for a complete description).